Sofa



FIG. 1 is a front view of the design for a sofa;

FIG. 2 is a rear view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a right perspective view thereof;

FIG. 8 is a left perspective view thereof;

FIG. 9 is a right perspective view of the sofa in an extended position; and,

FIG. 10 is a left perspective view of the sofa in the extended position.

The dotted lines shown on the article represent topstitching. The broken lines shown in the drawings are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a sofa, as shown and described. 